Automatic rhythm instrument

ABSTRACT

An automatic rhythm instrument comprises a clock pulse generator, a tempo control for controlling the period of the clock pulse, a rhythm pattern pulse encoder receiving the clock pulse and generating rhythm pattern pulses for the selected rhythm, tone generators for generating tone signals, and tone keyers for gating tone signals upon receipt of the rhythm pattern pulses. On each pulse of the rhythm pattern pulses, the tone keyer conducts for a time period determined by a time constant circuit included therein. The tempo control is also connected to the time constant circuit to vary the conducting time lengths of the tone keyers in accordance with the tempo by the tempo control, so that each sounding time length becomes shorter as the tempo becomes faster.

United States Patent 91 111 3,742,112 Okamoto June 26, 1973 AUTOMATIC RHYTHM INSTRUMENT 3,629,480 12/1971 Harris 84/103 [75] Inventor: Elsaku Okamoto, Hamakita, Japan Primary Examiner kichard B Wilkinson [73] Assignee: Nippon Gakki Seigo Kabushiki Assistant Examiner-Stanley .l. Witkowski Kaisha, l-lamamatsu-shi, Japan Attorney-Holman & Stern [22] Filed: Oct. 26, 1971 ABSTRACT [21] APPI N04 192,161 An automatic rhythm instrument comprises a clock pulse generator, a tempo control for controlling the pe- [30] Foreign Application Priority Data l'iod the 5 P2 y g P p fi Encoder receivmg t e 0 oc pu se an generatmg r yt m pat- Oct. 27, 1970 Japan 45/93983 tem pulses for the selected y tone generators for [52] US. Cl. 84/ 1.03 generating tone g and tone keyers for gating tone [51] Int Cl 0 I n Glob U00 signals upon receipt of the rhythm pattern pulses. On 58 Field of Search 84/1.01, 1.03, 1.24 each Pulse Patter" l the 9" conducts for a time period determmed by a time cons- [561 il'ifniifittiflfi325E221;IZEFEJJfiiLS112? UNITED STATES PATENTS ducting time lengths of the tone keyers in accordance R26,52l 2/1969 Park 84/103 the tempo the tempo control so that each 3,358,068 12/1967 Campbell 84/1.0l di i l th b omes shorter as the tempo be- 3,482,027 12/1969 Okamoto et al. 84/103 comes faster 3,549,774 12/1970 Bunger 84/l.03 3,549,776 12/1970 Shiga et a1. 84/].03 4 Claims, 12 Drawing Figures l TONE TONE -ouT GENERATORS KEY ERS 3 4 5 T CLOCK RHYTHM TEMPOL PULSE P PATTERN CONTRO GENERATOR [PULSE EN CODER mimimuuzs ms 3,742.1 12

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{I 2 ToNE ToNE our GENERATORS KEYERS 3 4 CLOCK RHYTHM TEMPO PLLSE P PATTERN CONTROL GENERATOR PULSE ENCODER FIG. 6(A) 4 RHYTHM PATTERN PULSE ENCODER F l G. 6(8) PAIENTEflwaes I973 3,742.1 12

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I 7 I3 lllllllllllll I I3 lllllllllllllllll-lllllll $4M I\ U AUTOMATIC RHYTHM INSTRUMENT BACKGROUND OF THE INVENTION This invention relates generally to an automatic rhythm instrument, and more particularly to a new and advanced automatic rhythm instrument wherein the sounding time length of each tone is varied automatically in accordance with the tempo of the rhythm.

As conducive to a full understanding of the nature and utility of this invention, the following background description is first presented in some detail with respect to specific examples of the prior art as illustrated in FIGS. 1 through 4, briefly described hereinafter.

One example of an automatic rhythm instrument known heretofore is of a circuit organization as indicated in FIG. 1. In this circuit, rhythm rendition is accomplished by extracting tone signals from tone generators 1 through tone keyers 2 triggered rhythmically by rhythm pattern pulses. The switching (opening and closing) operation of the tone keyers 2 are triggered by gating signals, which gating signals are produced by encoding at conventional rhythm pulse encoder the clock pulse signals generated at a clock pulse generating circuit 4 being controlled by a tempo control circuit 3. Numerous examples of such rhythm pulse encoders can be found in the patent literature, such as in U.S. Pat. Nos. 3,358,068; 3,482,027; 3,549,774; 3,549,776; 3,624,263; and 3,646,242, all commonly assigned.

In one example as illustrated in FIG. 2 of a specific circuit constituting the tempo control circuit 3 and the clock pulse generating circuit 4 shown in FIG. 1, the

clock pulse generating circuit 4 is formed by an astable multivibrator, while the tempo control circuit 3 is adapted to vary the base-circuit voltage of the two transistors in the stable multivibrator by means of a variable resistance VR thereby to adjust the period of the clock pulses.

Specific examples of the tone keyers 2 for accomplishing gating operation of the tone signals in accordance with rhythm pattern pulses formed by the rhythm pattern pulse encoder circuit 5 upon receiving clock pulses from the clock pulse generating circuit 4 are shown in FIGS. 3(A), 3(8), and 3(C). Each of these tone keyers include a one-shot multivibrator having a time constant circuit consisting of a capacitor C, and a resistor R, as well as a gating circuit connected with the one-shot multivibrator, thereby carrying out circuit opening and closing operation in response to pulses sent from the one-shot multivibrator which is triggered by signals imparted through a trigger input terminal TI. The one-shot multivibrator delivers a pulse having a time length t which is approximately equal to 0.7 C,R,, and the gating circuits in FIGS. 3 (A) and (B) will conduct the tone signal for a period of time having the time length I. The gating circuit constituted by diode D, variable resistor VR, and capacitor C in FIG. 3(C) exhibits a gating operation having a decaying envelope, the decaying time 1- being determined primarily by capacitor C and variable resistor VR. As a result, the musical tone signals applied to the input terminal IN are gated and are obtained as rhythm playing signals at the output terminal OUT.

The relationships between the clock pulses in the circuits shown in FIGS. 3(A), 3(8), and 3(C) and the sounding time lengths of the tone signal (or decaying time lengths) are indicated in FIGS. 4(A) and 4(3). FIG. 4(A) indicates the gating manners of the tone keyer 2 illustrates in FIGS. 3(A) and 3(8), while FIG. 4(B) indicates the gating manner of the tone keyer 2 shown in FIG. 3(C). In FIGS. 4(A) and 4(8), symbol character P represents clock pulses of from 2 to 14 Hz (periods: from 500 ms to ms); t denotes the sounding time length; and 1 denotes the decaying time length. The charts (a) depict the relationship between the clock pulses and the gating envelopes at a slow tempo, while chart (b) depicts the relationship between the same parameters at a fast tempo. Here, the sounding time t and the decaying time 1' are constant, irrespective of the magnitude of the rhythm period, that is, unrelated to the tempo.

Accordingly, in the case where the tempo of the rhythm is slow, the emitted tones can be clearly and accurately distinguished, and a clear rhythm effect is obtained. When the tempo is made faster, however, the tones emitted are mutually superimposed, and the rhythm sensation is lost. For this reason, when the tempo is increased, a rhythm which should, in general, impart a buoyant, pleasant sensation to listeners imparts, on the contrary, a heavy, slow sensation, whereby the entire musical rendition effect becomes deficient.

SUMMARY OF THE INVENTION It is an object of this invention to overcome the above described difficulty by providing an automatic rhythm instrument of a novel circuit organization whereby, in a preferred example thereof, a variable resistance for tempo control for varying clock pulse period and that for the time-constant circuit of a one-shot multivibrator in a tone keyer are operated in intercoupled relationship, whereby the sounding time length can be varied in accordance with the tempo.

According to this invention, briefly but more specifically summarized, there is provided an automatic rhythm instrument comprising a clock pulse generator circuit for generating periodic pulses, a tempo control circuit for controlling the pulse generating period of the clock pulse circuit, a rhythm pattern pulse encoder receiving clock pulses from the clock pulse circuit and generating rhythm pattern pulses in accordance with a selection of rhythm kinds,'and tone keyers gated by the rhythm pattern pulses thus generated for a conducting time length controlled by the tempo control circuit and operating to transmit musical tone signals from tone generators only during the conducting time.

The nature, principle, and utility of the invention will be more clearly apparent from the following detailed description with respect to a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. I is a block diagram showing the essential organization of one example of a known automatic rhythm instrument;

FIG. 2 is a schematic diagram showing an example of a clock pulse generator in the instrument illustrated in FIG. 1;

FIGS. 3(A), 3(8), and 3(C) are schematic diagrams showing respective examples of tone keyers in the same instrument;

FIGS. 4(A) and 4(8) are pulse time charts indicating relationships between clock pulsesand tone sounding time lengths in the same instrument;

FIG. 5 is a block diagram showing the essential organization of one example of an automatic rhythm instrument according to the invention;

FIGS. 6(A) and 6(8) are schematic diagrams respectively showing examples of the clock pulse generator and the tone keyer in the instrument illustrated in FIG. 5; and

FIGS. 7(A) and 7(8) and pulse time charts indicating relationships between clock pulses and tone sounding time length in the instrument according to this invention.

DETAILED DESCRIPTION In the example of a rhythm instrument according to this invention as illustrated in FIG. 5, the component circuits from 1 through 5 are similar to those of the known device shown in FIG. 1, but the tempo control circuit 3 and the tone keyer 2 are in intercoupled relation.

Specific examples of circuit organization of the instrument shown in FIG. 5 are illustrated in FIG. 6, in which FIG. 6(A) shows the circuit organization in the case where the tone sounding time length is controlled, while FIG. 6(B) shows that in the case where the decaying time length is controlled.

In the arrangement shown in FIG. 6(A), the clock pulse generator circuit 4 comprises, for example, an astable multivibrator having two transistors Q and 0, By varying the voltage of the base circuits of these transistors by means of the variable resistance VR of the tempo control circuit 3, clock pulses P of different periods can be selectively generated. These clock pulses P are applied to the rhythm pattern pulse encoder 5 and transformed into selected pattern pulse signals in accordance with a desired rhythm.

These pattern signals are selectively determined beforehand by the musician operating the device in accordance with the musical selection and other factors (as provided in known instruments) and are applied to the trigger input terminal Tl of the tone keyer 2. The one-shot multivibrator in the tone keyer 2 thereby forms pulse signals, in accordance with which the transistor Q (keyer transistor) is caused to assume ON and OFF states.

The time-constant circuit (including C, and R,) of the one-shot multivibrator in this case is connected to the sliding contact .of the variable resistance VR in the tempo control circuit 3. For this reason, the pulse width of the pulse signals formed by the one-shot multivibrator varies depending on the position of the sliding contact of the resistance VR. Accordingly, this position is so set that the ON time of the transistor 0 (this time period becomes the sounding length time) shortens with the tempo control in such a manner that the pulse width becomes small when the tempo is fast.

As a result, a inusical tone signal introduced into the tone keyer through the input terminal IN is sent out through the output terminal OUT only during the ON time of the transistor 0,, and the sounding time length varies with the tempo control. Variations of the sounding time length due to the tempo are indicated in FIG. 7. When the tempo is slow as indicated in FIG.

the sounding time length within a range of two times.

A circuit organization for the case of decaying-time control is shown in FIG. 6(B). This circuit is of the same construction as that depicted in FIG. 3(C) except that a field-effect transistor PET is now included in place of the variable resistor VR'. A field-effect transistor FET is used as a voltage controlled variable resistor in the tone keyer 2 and is of an organization such as to carry out percussive envelopeoperation in accordance with the transmission of the pulse signals from the oneshot multivibrator. The gate of the field-effect transistor FET is in this case connected to the sliding contact of the variable resistance VR of the tempo control circuit 3. For this reason, the internal resistance of the field-effect transistor F ET varies with tempo control by means of the same variable resistance VR.

Accordingly, after reception of a pulse signal from the one-shot multivibrator, the time required for recovery of the voltage between the terminals of the capacitor C also varies. As a result, the decaying time length of the tone keyer 2 becomes as T when the tempo is 7(A)(a), the sounding time length r, is long, while when the tempo is fast as indicated in FIG. 7(A)(b), the sounding time length I, is short. Even in the case where the range of variation of the tempo is more than two times, it will be sufficient in actual practice to vary slow, as indicated in FIG. 7(B)(a), and becomes short as T when the tempo is fast, as indicated in FIG. 7(B)(b).

Thus, as described above, this invention affords variation of the sounding time lengths or decaying time lengths of musical tones to match the tempo of the rhythm, lengthening the time when the tempo is slow, and shortening the time when the tempo is fast. As a result, balance between the tempo and the sounding times is achieved, and excellent rendition effects are attainable. Moreover, the circuit organization according to this invention is such as to employ circuit components of the same order as those used in known circuits of like class, whereby the device of this invention does not entail high production costs.

I claim:

1. An automatic rhythm instrument comprising:

a clock pulse generator means for generating periodic clock pulses of a tempo;

a tempo control means for controlling the period of said clock pulses;

a rhythm pattern pulse encoder means connected to said clock pulse generator for generating rhythm pattern pulses;

tone generator means for generating tone signals; and

tone keyer means connected respectively to said tone generator means and to said rhythm pattern pulse encoder means for gating tone signals in response to said rhythm pattern pulses, said tone keyer means including a controllable time constant'circuit determining the conducting time length of the keyer and permitting each said tone signal to sound for a predetermined time length upon receipt of each said pulse, said time constant circuit being connected with said tempo control means so that said time length thereof is controlled in accordance with the tempo by said tempo control means.

2. An automatic rhythm instrument according to claim 1 in which: the clock pulse generator means comclaim 2 in which the tone keyer means has a field-effect 5 transistor used as an active element therein, said fieldeffect transistor having a gate connected to the sliding contact of the variable resistance in the tempo control means. 

1. An automatic rhythm instrument comprising: a clock pulse generator means for generating periodic clock pulses of a tempo; a tempo control means for controlling the period of said clock pulses; a rhythm pattern pulse encoder means connected to said clock pulse generator for generating rhythm pattern pulses; tone generator means for generating tone signals; and tone keyer means connected respectively to said tone generator means and to said rhythm pattern pulse encoder means for gating tone signals in response to said rhythm pattern pulses, said tone keyer means including a controllable time constant circuit determining the conducting time length of the keyer and permitting each said tone signal to sound for a predetermined time length upon receipt of each said pulse, said time constant circuit being connected with said tempo control means so that said time length thereof is controlled in accordance with the tempo by said tempo control means.
 2. An automatic rhythm instrument according to claim 1 in which: the clock pulse generator means comprises an astable multivibrator; the tempo control means comprises a variable resistance with a sliding contact for varying the resistance; and the tone keyer means comprises a one-shot multivibrator for determining the sounding time length.
 3. An automatic rhythm instrument according to claim 2 in which the time-constant circuit includes a capacitor and a resistor, the resistor being connected to the sliding contact of the variable resistance in the tempo control means.
 4. An automatic rhythm instrument according to claim 2 in which the tone keyer means has a field-effect transistor used as an active element therein, said field-effect transistor having a gate connected to the sliding contact of the variable resistance in the tempo control means. 